Two bicyclists of unequal ability often have difficulty staying together while riding. To remedy this situation, many cyclists couple their bicycles together in a tandem arrangement in order to combine efforts and stay together for all or a part of the ride. In the latter case, the bicycles may be decoupled later in the ride, enabling independent riding on the same trip. This situation is common not only for adults riding with children but also for adults riding with other adults of differing cycling ability. Currently, no convenient, lightweight, and safe device exists that provides coupling and decoupling capability when both riders weigh in excess of approximately 90 pounds.
A number of designs exist that permit a bicycle to pull a single-wheel type of trailer with handlebars for a small child to ride. See, for example, U.S. Pat. Nos. 5,067,738 and 5,470,088. While such designs may allow the child to peddle and contribute to the ride, they do not provide capability for the child to ride independently if desired. In addition, such designs have a weight limit that is typically below 90 pounds due to the imbalance that can occur with larger riders on the trailing device since the leading cyclist must provide balance for both riders.
U.S. Pat. No. 6,155,582 discloses a device for towing a child's bicycle in which the front wheel of the child's bicycle is lifted off the ground. This coupling device includes features for relatively quick removal and stowage of the device on the lead bicycle. However, this device also limits the weight of the child rider for the same reasons as the single-wheel trailer type design noted above. In addition, because the tow bar must bear a part of the load necessary to lift the front wheel of the trailing bicycle throughout the ride, the tow bar is necessarily relatively heavy and inconvenient to stow on the lead bicycle when not in use.
A number of devices for coupling two bicycles into a tandem configuration using a linking bar and flexible connection arrangement are known. See U.S. Pat. Nos. 4,261,592, 5,749,592, 6,036,215 and 6,286,847. However, these designs also have a significant drawback in that the linking bar is substantially nonextendable in its longitudinal axis. When two separate bicycles are ridden in alignment one behind the other at equal speeds, the position of one bicycle relative to the other continually changes along the longitudinal axis between the bicycles as each bicycle encounters slightly different road conditions. These changes in relative position along the longitudinal axis can be minor if road conditions are excellent, or very substantial under poor road conditions, e.g., when one bicycle rolls over a bump or a rut. Because a fixed linking bar does not allow flexibility and load-dampening along its longitudinal axis, each bicycle will transmit its own de-stabilizing axial forces directly to the other, creating a less stable and less comfortable ride and resulting in a potential crash when road conditions are poor. In addition, when the lead bicycle is turning sharply, it can be difficult for the trailing bicycle to follow directly behind the lead bicycle, particularly at higher speeds. When this occurs, the directions of travel of each bicycle can quickly diverge, creating a very unstable situation which usually results in both bicycles falling. Thus, this design does not provide for a means to decouple the bicycles or otherwise prevent such an unsafe situation.
U.S. Pat. No. 6,036,215 discloses a means of separating a tandem linking bar based on axial tensile forces exceeding a certain limit. However, this type design can result in an unintended separation when the lead bicycle rider is strenuously towing a heavily loaded trailing bicycle or is towing up a steep incline. Conversely, if the release force needed to separate is high enough to permit the linking bar to remain intact while towing a substantial load, this could have the unintended effect of not detaching should a smaller trailing bicycle and rider fall.
There is therefore a need in the art for a tandem bicycle coupling device with a combination of minimal weight, small profile, and quick. and easy engagement and disengagement that allows safe decoupling and allows for an unequal distribution of forces between the coupled bicycles. These needs and others which will become apparent to one skilled in the art are provided by the present invention, which is summarized and described in detail below,